New Application/Method

Someone by the moniker of Blend3r contacted me with a new method of rooting both the NVG510 and NVG589 modems. It does require downgrading the firmware, but it looks easy enough to execute. He provides a Java app, or a write up on how to do it manually. I did a cursory check through the Java code while writing this, but he can of course change it at anytime. I trust him enough to link to him, but if you're security paranoid it is best to do the DIY method instead of using his app.

Do not contact me about problems with his tool/method unless you think it's a virus or something like that (so I can unlink it). I looked through it and it makes sense to me, but I by no means support any of these. Don't ask me for help on how to do it, etc etc.

UNSUPPORTED

Sometime ago, my app got pulled from Google Play. That really bummed me out, then AT&T published a new firmware update fixing all of my known exploits. And well, I just haven't had the motivation to try to find another. I'll leave everything up for reference, and if you downgrade your firmware, maybe it'll work... but I have no idea. I haven't touched my NVG510 in at least 6 months. So, you're on your own. If you end up finding another exploit or can help people here, please give me a link and I can point people to your website.

I have no intentions of picking back up on rooting the NVG510 and NVG589.

One-click Android Application

The fix to common problems with the NVG510 and NVG589 is now available as a push-button $3 Android app called NVG510 Fixer. You can see more information at this blog post. If you don't think it's worth it though, (or want to do crazy technical things), just stick with the free instructions on this page

Updated for new firmware! :)

This guide has been tested to work with the following hardware and firmware:

NVG510 9.0.6h2d30

NVG510 9.0.6h2d21

NVG510 9.0.6h048

NVG589 (unknown)

It's very possible that other Netopia OS based modems are affected as well. There is a Netopia modem used in Switzerland that probably can be rooted with this.

How to root the modem

Warning

WARNING: This is information on how to root your modem. Rooting is to take full control, like rooting your Android phone. It can possibly brick your modem if not used responsibly. USE AT YOUR OWN RISK

Take the "value" of the nonce and put it into the text field labeled nonce on the page. 815a0aaa0000176012db85d7d7cac9b31e749a44b6551d02 would be what you put into it for this example.

Load the page up and push Save.

At this point, you might see different things, depending on your browser. You might get a message that the page couldn't be displayed, or you might see some text. If you see the text, make sure that it says "backdoor telnet enabled" or some such. You might also just see the normal Web Update interface with a "invalid firmware image" message. This is nothing to worry about either.

From here, you can do a few different things. This shell is called nsh. If you want to get to a root shell, just type !. At that point, you can do exit to get back to nsh.
Also, if you prefer the shell described in the FCC manual (and used by AT&T techs), you can type cshell after getting to the root shell.

How does it work?

I've found a vulnerability in the WebUI of the NVG510 (and other modems) that allows me to execute any command as root. You can utilize this by sending it a specially crafted HTTP request.

So, I use this to download the shell
script at http://earlz.net/static/backdoor.nvg510.sh and execute it on the modem. What the shell script does is it will install a new service into inetd so that it starts a telnet
shell, and I configure it using pfs to be persistent. Otherwise, it would go away after rebooting.

Uninstalling the backdoor

The backdoor installed should be fairly safe, being password protected, but if you're especially worried, then it can easily be uninstalled.
Just telnet into the modem, get to the root shell by using !, and then type:

pfs -r /var/etc/inetd.d/telnet28

Note! This backdoor will not be uninstalled with a factory reset or firmware update!. Once you've installed it, it's there until you uninstall it! Again, there should be no risk in leaving it there,
it will not be internet accessible. But, it's easy to uninstall as well.

Solving common problems

To confirm you're at nsh, you should see a prompt like this:

Axis/1234565678>

The nsh Console

This console is fairly simple and easy to use, and breaks out everything that you can configure on the modem. But, it is not the console described in the FCC manual.

This is the help text for the console, to help you understand:

Axis/124578433> help
help [command] : Get help.
history : Show command history.
get OBJ.ITEM : Get the value of OBJ.ITEM (ITEM is a
parameter or status). ### Hint: run 'info
OBJ.params' or 'info OBJ.status' to get a
list of the OBJ's parameters and status.
set OBJ.ITEM VALUE : Set the value of OBJ.ITEM to VALUE.
info INFO [ARGS ...] : Get the INFO information (expert mode).
new OBJ [NAME] : Create an object with an (optional) name
(requires an 'apply')
del OBJ : Delete an object (requires an 'apply')
aget OBJ.ITEM ATTR : Get the OBJ.ITEM's ATTR attribute.
aset OBJ.ITEM ATTR VALUE : Set the OBJ.ITEM's ATTR attribute to VALUE.
name OBJ [NAME] : Get or set the OBJ's "name" (specify a new
name to set it).
names [OBJ] : Recursively show all object names.
validate [OBJ] : Validate OBJ, or the entire database if no
OBJ specified.
apply : Apply changes to the database (changes are
NOT saved).
revert : Revert the database by discarding your
changes.
save : Save the database (rewrites config.xml).
defaults : Reset the system back to the factory
defaults (deletes config.xml).
dump [OBJ [LEVELS]] : Dumps the OBJ's parameters, or the entire
database. Use the optional LEVELS parameter
to limit the depth of the database tree.
sdump [OBJ [LEVELS]] : Dumps the OBJ's status, or the entire
database.
tdump [TEMPLATE [LEVELS]] : Dumps the template, or the entire SDB schema.
dirty [OBJ] : Displays which parameters are dirty.
run CMD [ARGS ...] : Run the SDB's CMD command (expert mode
only!).
event EVT [ARGS ...] : Send the EVT (event number) to the SDB
(expert mode only!).
console [on | off] : Direct all log messages to this console.
Without arguments, toggles on and off.
log [OPTIONS] : View log messages. See "log help" for more
information.
voiplog [OPTIONS] : View log messages. See "log help" for more
information.
mfg [OPTIONS] : Set or view MFG parameters. See "mfg help"
for more information.
mirror [PORT CAPTURE-PORT] | "off" : Mirror Ethernet traffic on PORT so that it
may seen on CAPTURE-PORT. Specify "off" to
turn mirroring off.
resetstats [OBJ] ["all"] : Reset any statistics the object may have.
The optional "all" argument will recursively
reset all children's stats as well. If only
"all" is given (OBJ is omitted), this will
reset all statistics starting at the root
node.
metadata OBJ.PARAM : Returns metadata information about a given
parameter.
fwinstall URL | "last" : Install a firmware image. Use "last" to
reuse the last URL.
crashdump ["erase"] : Shows the most recent crash dump contents.
The optional "erase" will erase both current
and last saved crash dump contents.
reboot [N] | ["cancel"] : Reboot the router in N seconds (default is
2). "cancel" argument can be issued to
cancel a previous reboot command.
source FILE : Read and process commands from FILE.
. FILE : An alias for 'source'.
exit : Exit from this shell.
quit : An alias for 'exit'.
magic : Enter magic mode.
crash : Read and Write the Memory mapped registers

Seems simple enough then doesn't it?

Example Configuration

So, let's say you want to enable SSH. The relevant configuration option for this is mgmt.shell.ssh-port. So, to set this, we type this in:

set mgmt.shell.ssh-port 22

This will set the SSH port to 22, rather than disabled. And then, if you're done configuring, you can save and apply the changes by typing these commands in:

validate
apply
save

You don't necessarily have to do validate, but I assume it's safer to use it I think. I believe that this is what happens:

validate will validate the changes to make sure that no data was input in a way that wouldn't make sense (like if nameserver was set to 921.123.45.673)

apply will actually cause the modem to notice the changes and begin executing using those changes you've made

save will cause the changes you made to persist after reboot. I assume it saves it to flash with this command.

That's really about all there is to know. Configuration is super simple.

Configuration

As you can tell from the dump log, there are a ton of configuration options. Here I'll give you a hint to the more useful ones, as well as some configuration stuff to be aware of

DNS problem fix

This is provided for historical reasons, but it's WRONG. This will not fix the DNS problems or let you point it at a different DNS server. I don't know why it doesn't work, but I've received multiple reports that it doesn't. Your best bet in this case is to use the true bridge mode and get your own router

You should be able to change these to something more appropriate. override-allowed should be turned on(otherwise I believe they will be reset by DHCP over the DSL link).

Enabling Telnet and/or SSH

mgmt.shell.ssh-port = 0
mgmt.shell.telnet-port = 0

These you should change to what port you want it to run on. Note though that I've yet to figure out the username and password used for SSH. I've searched through both the dump and through the GPL source code and can't find any hints really.

I haven't confirmed this, but I believe UPnP can be enabled by changing this to on:

mgmt.upnp.enable = off

Disable "Potential Connection Issue" warnings

mgmt.lan-redirect.enable = on

Change it to off. lan-redirect is what causes that extremely annoying redirecting to happen when the connection is lost or "has possible problems". What the modem will do is when you request a nameserver, it will, instead of sending back no route, timeout, or the actual name servers response,
it will instead make every domain forward to 192.168.1.254, so that you can then load an HTML page that causes a redirect(but doesn't set it to do-not-cache) to /cgi-bin/home.ha... So basically, you click do not show, yet the page continues to try to redirect
due to modern web browser caching and the lack of a no-cache directive on the redirect page.

Disabling the DHCP server

conn[1].dhcps-enable = on

Note that you'll have to configure a static IP to the modem to access it after this. I don't see much of a point in disabling it completely.

True Bridge Mode

A very often wanted feature of the NVG510 is for it to just get out of your way and let your (hopefully more sane) router to deal with all the firewall and NAT business. After quite a bit of experimenting and starting over with default and a bit of an accident, I believe I've figured it out.

Some of the values in the NVG510's configuration "database" appears to be magical, and lots of assumptions have to be made without real technical documentation. So, let's look at the link object that appears to be linked to WAN and LAN connections in an assumed manner.

Here is what was in my modem's dump about links. Your's should look similar:

The first command sets the LAN link so that only the LAN ports 2-4 is used. The next link sets the link for the WAN side of the link. Previously, the port is vc-1. I assume vc-1 is hardwired to magically go to the LAN somehow. Anyway, replacing vc-1 with lan-1 basically makes the equivalent of a PPP bridge.

On the router side, all you have to do is use that port and the modem will do all of the PPP authentication, and I assume MRU shifting to 1500.. All your modem will get is a raw stream from AT&T's servers. So if you send it a DHCP client request, you'll get a response straight from AT&T's servers.

This is the only configuration required as well. This will short through all of the modem's crappy configuration and directly forward it to the first ethernet port(the one closest to the barrel jack power adapter).

And if for some odd reason you need to access the actual modem(such as for reconfiguration), just plug your network cable into another port. The built-in DHCP server runs just as before, except it will never be connected to the internet.

Note: I've had reports that this doesn't completely work when your account is provisioned with multiple static IP addresses. If you have problems and are willing to lend me some time to test things with you, email me at earlz -AT- earlz dot net

Possible Problem: If your modem seems to "hang" when doing apply with the bridge mode configuration and you can't use the save command, then that means you tried to do it from port-1. Change which port on the NVG510 your computer is plugged into(or use Wifi if you're extra brave)

Other Dangerous Things

From this bootloader, you can change a lot of things AT&T probably would frown upon. Basically, you can make it look like another modem. I'm not for sure about this though and will have to test it and research it more. I don't recommend changing anything in the mfg section. If you do one of these kind of hacks, be prepared for AT&T to notice and ban you from U-Verse, your modem to become bricked, or for your dog to randomly die. Don't go too far into the dangerous looking unknown.

Conclusion

The NVG510 is really a decent modem, but has been kiddie-proofed so hard that it hurts. I hope this guide helps you to taking full control of your modem. Also, I don't recommend trying to evade your U-Verse accounts capabilities.
I imagine AT&T won't care much if they catch you modifying your modem... they will care if you modified it to reach 16Mbit speeds when you only have a 3Mbit account though, and I'm sure they keep tabs on it. Don't be stupid.

Same goes for trying to boost wifi power or use channels not specified for use in your country. The FCC is real! (btw, don't tell them about my FM transmitter project ;) )

Configuration Template
You can dump this for yourself, but to see what Motorola's "template" is for it's configuration options you can check out this pastebin. If you don't know what options a configuration object supports, this is a good bit to look at. Though a few things in the template don't exist in my NVG510 at least and will cause crashes if objects are created. (cifs will not work for me)

Older Versions

This is a new hack that should work on old firmware. However, if you're interested in the old hack(that only works on old firmware), you can see the wayback machine for a historical copy.